The present invention is directed to a coupling element for coupling light into and out of an optical fiber which has an end formed by a pair of end surfaces that extend at an angle to one another with one of the pair of end surfaces being essentially perpendicular to the axis of the optical fiber and the other end surface of the pair which end surface is inclined to the axis being provided with a reflective layer.
In the system fibers for an optical data bus which bus may be assumed to be realized as a star bus with a reflective mixer, light is to be coupled into the system fiber from the transmitter of the subscribers with as little loss as possible. In addition, light is to be coupled out of the system fiber to the receivers of the subscriber with a high degree of efficiency.